The USDA reports that 93% of all soy and 85% of all corn grown in the U.S. is an herbicide-resistant GE variety;

Similarly, around 93% of all cottonseed oil and more than 90% of all canola oil produced in the U.S. is herbicide-resistant GE.

However, it turns out that GE crops need a lot more herbicides than conventional ones.

Washington State University Charles Benbrook – former Executive Director of the Board on Agriculture at the National Academy of Sciences and, before that, Executive Director of the Subcommittee on Department Operations, Research, and Foreign Agriculture, U.S. House of Representatives – published a study showing:

Contrary to often-repeated claims that today’s genetically-engineered crops have, and are reducing pesticide use, the spread of glyphosate-resistant weeds in herbicide-resistant weed management systems has brought about substantial increases in the number and volume of herbicides applied. If new genetically engineered forms of corn and soybeans tolerant of 2,4-D are approved, the volume of 2,4-D sprayed [background] could drive herbicide usage upward by another approximate 50%.

***

Largely because of the spread of glyphosate-resistant weeds, HR crop technology has led to a 239 million kg (527 million pound) increase in herbicide use across the three major GE-HR crops, compared to what herbicide use would likely have been in the absence of HR crops.

Herbicide-tolerant crops worked extremely well in the first few years of use, but over-reliance led to shifts in weed communities and the emergence of resistant weeds that have, together, forced farmers to incrementally –

Increase herbicide application rates (especially glyphosate);

Spray more often, and;

Add new herbicides that work through an alternate mode-of-action into their spray programs.

Each of these responses has, and will continue to contribute to the steady rise in the volume of herbicides applied per acre of HT corn, cotton, and soybeans.

HT crops have increased herbicide use by 527 million pounds over the 16-year period (1996-2011). The incremental increase per year has grown steadily from 1.5 million pounds in 1999, to 18 million five years later in 2003, and 79 million pounds in 2009. In 2011, about 90 million more pounds of herbicides were applied than likely in the absence of HT, or about 24% of total herbicide use on the three crops in 2011.

Today’s major GE crops have increased overall pesticide use by 404 million pounds from 1996 through 2011 (527 million pound increase in herbicides, minus the 123 million pound decrease in insecticides). Overall pesticide use in 2011 was about 20% higher on each acre planted to a GE crop, compared to pesticide use on acres not planted to GE crops.

There are now two-dozen weeds resistant to glyphosate, the major herbicide used on HT crops, and many of these are spreading rapidly. Millions of acres are infested with more than one glyphosate-resistant weed. The presence of resistant weeds drives up herbicide use by 25% to 50%, and increases farmer-weed control costs by at least as much.

The biotechnology-seed-pesticide industry’s primary response to the spread of glyphosate-resistant weeds is development of new HT varieties resistant to multiple herbicides, including 2,4-D and dicamba. These older phenoxy herbicides pose markedly greater human health and environmental risks per acre treated than glyphosate. Approval of corn tolerant of 2,4-D is pending, and could lead to an additional 50% increase in herbicide use per acre on 2,4-D HT corn.

A new study released by Food & Water Watch yesterday finds the goal of reduced chemical use has not panned out as planned. In fact, according to the USDA and EPA data used in the report, the quick adoption of genetically engineered crops by farmers has increased herbicide use over the past 9 years in the U.S. The report follows on the heels of another such study by Washington State University research professor Charles Benbrook just last year.

Both reports focus on “superweeds.” It turns out that spraying a pesticide repeatedly selects for weeds which also resist the chemical. Ever more resistant weeds are then bred, able to withstand increasing amounts – and often different forms – of herbicide.

GE Crops Have Reduced Crop Productivity

GE food manufacturers also promised an increase in crop productivity. Indeed, that was a giant selling point for GE foods.

Genetic modification actually cuts the productivity of crops, an authoritative new study shows, undermining repeated claims that a switch to the controversial technology is needed to solve the growing world food crisis.

The study – carried out over the past three years at the University of Kansas in the US grain belt – has found that GM soya produces about 10 per cent less food than its conventional equivalent, contradicting assertions by advocates of the technology that it increases yields.

Professor Barney Gordon, of the university’s department of agronomy, said he started the research – reported in the journal Better Crops – because many farmers who had changed over to the GM crop had “noticed that yields are not as high as expected even under optimal conditions”. He added: “People were asking the question ‘how come I don’t get as high a yield as I used to?’”

***

The new study confirms earlier research at the University of Nebraska, which found that another Monsanto GM soya produced 6 per cent less than its closest conventional relative, and 11 per cent less than the best non-GM soya available.

***

A similar situation seems to have happened with GM cotton in the US, where the total US crop declined even as GM technology took over.

***

Last week the biggest study of its kind ever conducted – the International Assessment of Agricultural Science and Technology for Development – concluded that GM was not the answer to world hunger.

Professor Bob Watson, the director of the study and chief scientist at the Department for Environment, Food and Rural Affairs, when asked if GM could solve world hunger, said: “The simple answer is no.”

For years the biotechnology industry has trumpeted that it will feed the world, promising that its genetically engineered crops will produce higher yields.

***

That promise has proven to be empty …. [A UCS report] reviewed two dozen academic studies of corn and soybeans, the two primary genetically engineered food and feed crops grown in the United States. Based on those studies, the UCS report concludes that genetically engineering herbicide-tolerant soybeans and herbicide-tolerant corn has not increased yields. Insect-resistant corn, meanwhile, has improved yields only marginally. The increase in yields for both crops over the last 13 years, the report finds, was largely due to traditional breeding or improvements in agricultural practices.

***

The report does not discount the possibility of genetic engineering eventually contributing to increase crop yields. It does, however, suggest that it makes little sense to support genetic engineering at the expense of technologies that have proven to substantially increase yields, especially in many developing countries. In addition, recent studies have shown that organic and similar farming methods that minimize the use of pesticides and synthetic fertilizers can more than double crop yields at little cost to poor farmers in such developing regions as Sub-Saharan Africa.

The report recommends that the U.S. Department of Agriculture, state agricultural agencies, and universities increase research and development for proven approaches to boost crop yields. Those approaches should include modern conventional plant breeding methods, sustainable and organic farming, and other sophisticated farming practices that do not require farmers to pay significant upfront costs. The report also recommends that U.S. food aid organizations make these more promising and affordable alternatives available to farmers in developing countries.

“If we are going to make headway in combating hunger due to overpopulation and climate change, we will need to increase crop yields,” said Gurian-Sherman. “Traditional breeding outperforms genetic engineering hands down.”

In a new paper (PDF) funded by the US Department of Agriculture, University of Wisconsin researchers have essentially negated the “more food” argument as well. The researchers looked at data from UW test plots that compared crop yields from various varieties of hybrid corn, some genetically modified and some not, between 1990 and 2010. While some GM varieties delivered small yield gains, others did not. Several even showed lower yields than non-GM counterparts. With the exception of one commonly used trait — a Bt type designed to kill the European corn borer — the authors conclude, “we were surprised not to find strongly positive transgenic yield effects.” Both the glyphosate-tolerant (Roundup Ready) and the Bt trait for corn rootworm caused yields to drop.

Then there’s the question of so-called “stacked-trait” crops—that is, say, corn engineered to contain multiple added genes—for example, Monsanto’s “Smart Stax” product, which contains both herbicide-tolerant and pesticide-expressing genes. The authors detected what they call “gene interaction” in these crops—genes inserted into them interact with each other in ways that affect yield, often negatively. If multiple genes added to a variety didn’t interact, “the [yield] effect of stacked genes would be equal to the sum of the corresponding single gene effects,” the authors write. Instead, the stacked-trait crops were all over the map. “We found strong evidence of gene interactions among transgenic traits when they are stacked,” they write. Most of those effects were negative — i.e., yield was reduced.

Overall, the report uncovers evidence of what is known as “yield drag” — the idea that manipulating the genome of a plant variety causes unintended changes in the way it grows, causing it to be less productive.

***

Here’s how the authors of a major paper published in Nature[one of the world's leading science journals] last year put it:

Soils managed with organic methods have shown better water-holding capacity and water infiltration rates and have produced higher yields than conventional systems under drought conditions and excessive rainfall.

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